f:convertDateTime support for Java8 LocalDate / LocalDateTime? [duplicate]

Answer 1

Just write your own Converter and extend the javax.faces.convert.DateTimeConverter - that way you can Reuse all the attributes that <f:convertDateTime> supports. Also it will take care of Localization too. Unfortunately it's a bit more complicated to write a Converter with Attributes.

Create component
First write your own Converter that extends javax.faces.convert.DateTimeConverter - just let the super-calls do all the work (including locale-stuff) and convert the result from/to LocalDate.

@FacesConverter(value = LocalDateConverter.ID)
public class LocalDateConverter extends DateTimeConverter {
    public static final String ID = "com.example.LocalDateConverter";

    @Override
    public Object getAsObject(FacesContext facesContext, UIComponent uiComponent, String value) {
        Object o = super.getAsObject(facesContext, uiComponent, value);

        if (o == null) {
            return null;
        }

        if (o instanceof Date) {
            Instant instant = Instant.ofEpochMilli(((Date) o).getTime());
            return LocalDateTime.ofInstant(instant, ZoneId.systemDefault()).toLocalDate();
        } else {
            throw new IllegalArgumentException(String.format("value=%s could not be converted to a LocalDate, result super.getAsObject=%s", value, o));
        }
    }

    @Override
    public String getAsString(FacesContext facesContext, UIComponent uiComponent, Object value) {
        if (value == null) {
            return super.getAsString(facesContext, uiComponent,value);
        }

        if (value instanceof LocalDate) {
            LocalDate lDate = (LocalDate) value;
            Instant instant = lDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant();
            Date date = Date.from(instant);
            return super.getAsString(facesContext, uiComponent, date);
        } else {
            throw new IllegalArgumentException(String.format("value=%s is not a instanceof LocalDate", value));
        }
    }
}

Then create a file LocalDateConverter-taglib.xml in META-INF:

<facelet-taglib version="2.2"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-facelettaglibrary_2_2.xsd">

    <namespace>http://example.com/LocalDateConverter</namespace>
    <tag>
        <tag-name>convertLocalDate</tag-name>
        <converter>
            <converter-id>com.example.LocalDateConverter</converter-id>
        </converter>
    </tag>
</facelet-taglib>

And lastly, register the taglib in web.xml:

<context-param>
    <param-name>javax.faces.FACELETS_LIBRARIES</param-name>
    <param-value>/META-INF/LocalDateConverter-taglib.xml</param-value>
</context-param>

Usage
To use the new Tag in your JSF-Page add the new Taglib xmlns:ldc="http://example.com/LocalDateConverter" and use the tag:

<ldc:convertLocalDate type="both" dateStyle="full"/>